Pneumatic radial tires including polyester carcass with specified elongation and shrinkage

Abstract

When polyester fiber cords having elongations under loads of 0.5 g/d and 2.25 g/d within particular ranges and a heat shrinkage (177° C. 30 minutes) within a particular range are used in a carcass ply of a pneumatic radial tire, the ride comfortability, tire uniformity and tire appearance can simultaneously be improved.

What is claimed is: 
     
       1. A pneumatic radial tire comprising a tread, a belt arranged inside the tread and a radial carcass comprised of at least one carcass ply, said carcass ply including polyester fiber cords each characterized by having an elongation of not less than 1.2% under a load of 0.5 g/d, an elongation of not more than 6.0% under a load of 2.25 g/d and a heat shrinkage of not more than 2.0% under an initial load of 50 g at 177° C. for 30 minutes. 
     
     
       2. The pneumatic radial tire according to claim 1, wherein said elongation under a load of 0.5 g/d is not less than 1.4%, and said elongation under a load of 2.25 g/d is not more than 5.8%, and said heat shrinkage is not more than 1.8%.